1. Field of the Invention
This invention relates generally to the metal forming art and more particularly to an improved high energy rate counterblow forming machine.
2. Prior Art
A variety of high energy rate forming machines have been devised. Generally speaking, such machines have a pair of relatively massive forming members supported on a frame for relative movement toward and away from one another. Mounted on these members are forming die parts which are movable into work forming relation, wherein the die parts define a die cavity conforming to the desired shape of the finished work product to be formed, by relative movement of the forming members toward one another. In a forming operation, a work part to be formed is placed in one die part, and the forming members are impelled together at extremely high velocity by a highly compressed working fluid to bring the forming die parts into forming relation with very high kinetic energy. The work part is thereby subjected to a high intensity or high energy impact which causes the part to undergo plastic flow into conforming relation with the die cavity.
In some forming machines of this kind, one of the forming members is stationary and the other forming member is a movable forming ram or the like which is impelled toward the stationary member. The resulting impact of the movable member with the stationary member produces extreme impact loads on the machine which limit the maximum impact forming energy which the machines can withstand. Other forming machines employ two movable forming members or rams which are impelled toward one another with substantial equal kinetic energies to form work parts in such a way that the machines are not subjected to any unbalanced impact loads. These latter forming machines are commonly referred to as counterblow forming machines. My prior U.S. Pat. No. 3,404,555 discloses such a counterblow forming machine.
Proper operation of a counterblow forming machine presents two basic problems, namely, compression of the working fluid to the correct high pressure levels to impel the forming members toward one another with equal kinetic energies and simultaneous release of the forming members for movement in unison through their working or forming strokes under the force of the compressed working fluid. One method of compressing the working fluid is that described in my aforementioned patent. According to this method, the forming members move within pressure chambers in which the working fluid is confined at an initial high pressure. The fluid is further compressed to a higher pressure level suitable for work forming by retracting the forming members into their cylinders to cocked positions. The forming members are simultaneously released for high velocity movement in unison through their working strokes. Other high energy rate forming machines are described in U.S. Pat. No. 422,557 and U.S. Pat. No. 3,488,990.